Fig. 5.

Number of revertants in S. typhimurium TA98 upon exposure to a phenanthrene, b 1-methylphenanthrene, c 2-methylphenanthrene, d 3-methylphenanthrene and e 9-methylphenanthrene in absence (black bar) and presence (white bar) of 5% S9-mix. Bars represent means and vertical bars indicate the standard deviation of the mean (n = 3). The dotted horizontal line indicates threefold increase that is considered the threshold for concluding on the positive outcome for mutagenicity. In the absence of S9 mix, the test doses of 3-methyl-phenanthrene showed cytotoxicity so no data are presented. The results of at least four analyzable doses that were non-cytotoxic are presented in Table S2 in the supplementary material 1 showing negative results. PC positive control, 1 µg/plate 2AA with S9-mix and 10 µg/plate NF without S9-mix. SC solvent control, DMSO with and without S9-mix